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feat: graceful shutdown #1963

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merged 3 commits into from
Feb 5, 2021
Merged

feat: graceful shutdown #1963

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f82c217
feat: graceful shutdown
nabokihms Jan 26, 2021
65a8bf2
feat: graceful shutdown fixes
nabokihms Jan 26, 2021
6664b57
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nabokihms Feb 5, 2021
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113 changes: 77 additions & 36 deletions cmd/dex/serve.go
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Original file line number Diff line number Diff line change
Expand Up @@ -10,11 +10,14 @@ import (
"net"
"net/http"
"os"
"os/signal"
"strings"
"syscall"
"time"

"github.com/ghodss/yaml"
grpcprometheus "github.com/grpc-ecosystem/go-grpc-prometheus"
"github.com/oklog/run"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
"github.com/sirupsen/logrus"
Expand Down Expand Up @@ -68,6 +71,28 @@ func commandServe() *cobra.Command {
return cmd
}

func listenAndShutdownGracefully(logger log.Logger, gr *run.Group, srv *http.Server, name string) error {
l, err := net.Listen("tcp", srv.Addr)
if err != nil {
return fmt.Errorf("listening (%s) on %s: %v", name, srv.Addr, err)
}

gr.Add(func() error {
logger.Infof("listening (%s) on %s", name, srv.Addr)
return srv.Serve(l)
}, func(err error) {
logger.Debugf("starting gracefully shutdown (%s)", name)
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if err := l.Close(); err != nil {
logger.Errorf("gracefully close (%s) listener: %v", name, err)
}
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AFAIK the http server takes care of this, so you don't need to call close on the listener manually.

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My thought was about splitting listener closing error and server shutdown error. Maybe it is excessive.

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Listener closing now is a duty of a server.


if err := srv.Shutdown(context.Background()); err != nil {
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What happens if there is an active connection for an indefinite amount of time? Will this wait indefinitely? If so, we should probably add a timeout here.

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Yes, good catch. I hardcoded a one-minute timeout here. Please tell me if you want to make this configurable or increase the value.

logger.Errorf("gracefully shutdown (%s): %v", name, err)
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}
})
return nil
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}

func runServe(options serveOptions) error {
configFile := options.config
configData, err := ioutil.ReadFile(configFile)
Expand Down Expand Up @@ -302,21 +327,21 @@ func runServe(options serveOptions) error {
telemetryServ := http.NewServeMux()
telemetryServ.Handle("/metrics", promhttp.HandlerFor(prometheusRegistry, promhttp.HandlerOpts{}))

errc := make(chan error, 3)
var gr run.Group
if c.Telemetry.HTTP != "" {
logger.Infof("listening (http/telemetry) on %s", c.Telemetry.HTTP)
go func() {
err := http.ListenAndServe(c.Telemetry.HTTP, telemetryServ)
errc <- fmt.Errorf("listening on %s failed: %v", c.Telemetry.HTTP, err)
}()
telemetrySrv := &http.Server{Addr: c.Telemetry.HTTP, Handler: telemetryServ}
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I think defer httpServer.Close() should be called on each server in the main func as a general cleanup step and as a last resort to graceful shutdown.

if err := listenAndShutdownGracefully(logger, &gr, telemetrySrv, "http/telemetry"); err != nil {
return err
}
}

if c.Web.HTTP != "" {
logger.Infof("listening (http) on %s", c.Web.HTTP)
go func() {
err := http.ListenAndServe(c.Web.HTTP, serv)
errc <- fmt.Errorf("listening on %s failed: %v", c.Web.HTTP, err)
}()
httpSrv := &http.Server{Addr: c.Web.HTTP, Handler: serv}
if err := listenAndShutdownGracefully(logger, &gr, httpSrv, "http"); err != nil {
return err
}
}

if c.Web.HTTPS != "" {
httpsSrv := &http.Server{
Addr: c.Web.HTTPS,
Expand All @@ -327,35 +352,51 @@ func runServe(options serveOptions) error {
MinVersion: tls.VersionTLS12,
},
}

logger.Infof("listening (https) on %s", c.Web.HTTPS)
go func() {
err = httpsSrv.ListenAndServeTLS(c.Web.TLSCert, c.Web.TLSKey)
errc <- fmt.Errorf("listening on %s failed: %v", c.Web.HTTPS, err)
}()
if err := listenAndShutdownGracefully(logger, &gr, httpsSrv, "https"); err != nil {
return err
}
}

if c.GRPC.Addr != "" {
logger.Infof("listening (grpc) on %s", c.GRPC.Addr)
go func() {
errc <- func() error {
list, err := net.Listen("tcp", c.GRPC.Addr)
if err != nil {
return fmt.Errorf("listening on %s failed: %v", c.GRPC.Addr, err)
}
s := grpc.NewServer(grpcOptions...)
api.RegisterDexServer(s, server.NewAPI(serverConfig.Storage, logger))
grpcMetrics.InitializeMetrics(s)
if c.GRPC.Reflection {
logger.Info("enabling reflection in grpc service")
reflection.Register(s)
}
err = s.Serve(list)
return fmt.Errorf("listening on %s failed: %v", c.GRPC.Addr, err)
}()
}()
grpcListener, err := net.Listen("tcp", c.GRPC.Addr)
if err != nil {
return fmt.Errorf("listening (grcp) on %s: %w", c.GRPC.Addr, err)
}

grpcSrv := grpc.NewServer(grpcOptions...)
api.RegisterDexServer(grpcSrv, server.NewAPI(serverConfig.Storage, logger))
grpcMetrics.InitializeMetrics(grpcSrv)
if c.GRPC.Reflection {
logger.Info("enabling reflection in grpc service")
reflection.Register(grpcSrv)
}

gr.Add(func() error {
logger.Infof("listening (grpc) on %s", c.GRPC.Addr)
return grpcSrv.Serve(grpcListener)
}, func(err error) {
logger.Debugf("starting gracefully shutdown (grpc)")
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if err := grpcListener.Close(); err != nil {
logger.Errorf("failed to gracefully close (grpc) listener: %v", err)
}
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Same as above

grpcSrv.GracefulStop()
})
}

return <-errc
sig := make(chan os.Signal)
gr.Add(func() error {
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The library has a builtin signal actor, maybe we could use it.

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Fixed. The only thing that I dislike about helper is that I can't log the received signal immediately.

signal.Notify(sig, os.Interrupt, syscall.SIGTERM)
receivedSig := <-sig
logger.Infof("received %s signal, shutting down", receivedSig)
return nil
}, func(err error) {
close(sig)
})

if err := gr.Run(); err != nil {
return fmt.Errorf("run groups: %w", err)
}
return nil
}

var (
Expand Down
1 change: 1 addition & 0 deletions go.mod
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@ require (
github.com/lib/pq v1.9.0
github.com/mattermost/xml-roundtrip-validator v0.0.0-20201219040909-8fd2afad43d1
github.com/mattn/go-sqlite3 v1.14.6
github.com/oklog/run v1.1.0
github.com/pkg/errors v0.9.1
github.com/prometheus/client_golang v1.4.0
github.com/russellhaering/goxmldsig v1.1.0
Expand Down
2 changes: 2 additions & 0 deletions go.sum
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Original file line number Diff line number Diff line change
Expand Up @@ -253,6 +253,8 @@ github.com/modern-go/reflect2 v1.0.1/go.mod h1:bx2lNnkwVCuqBIxFjflWJWanXIb3Rllmb
github.com/morikuni/aec v0.0.0-20170113033406-39771216ff4c h1:nXxl5PrvVm2L/wCy8dQu6DMTwH4oIuGN8GJDAlqDdVE=
github.com/morikuni/aec v0.0.0-20170113033406-39771216ff4c/go.mod h1:BbKIizmSmc5MMPqRYbxO4ZU0S0+P200+tUnFx7PXmsc=
github.com/mwitkow/go-conntrack v0.0.0-20161129095857-cc309e4a2223/go.mod h1:qRWi+5nqEBWmkhHvq77mSJWrCKwh8bxhgT7d/eI7P4U=
github.com/oklog/run v1.1.0 h1:GEenZ1cK0+q0+wsJew9qUg/DyD8k3JzYsZAi5gYi2mA=
github.com/oklog/run v1.1.0/go.mod h1:sVPdnTZT1zYwAJeCMu2Th4T21pA3FPOQRfWjQlk7DVU=
github.com/oklog/ulid v1.3.1/go.mod h1:CirwcVhetQ6Lv90oh/F+FBtV6XMibvdAFo93nm5qn4U=
github.com/olekukonko/tablewriter v0.0.0-20170122224234-a0225b3f23b5/go.mod h1:vsDQFd/mU46D+Z4whnwzcISnGGzXWMclvtLoiIKAKIo=
github.com/onsi/ginkgo v1.4.0/go.mod h1:lLunBs/Ym6LB5Z9jYTR76FiuTmxDTDusOGeTQH+WWjE=
Expand Down